Solid Floor Construction

[adrian.groves]

Hi,

I am renovating my downstairs bathroom which includes correcting the original concrete floor. The room has always been cold with very cold floor tiles and I suspected the concrete floor was damp.

It appears that the floor structure is a concrete slab with what looks like roof tiles on top and then a screed on top of those. The bathroom is an extension built in the 80's by the previous owner. Has anyone come across anything similar before?

I intend removing the rest of the screed /tiles and wondering what would be suitable to put on top of the concrete (which is 70mm below finished floor level)

I am contemplating using an extruded polystyrene insulation of 50mm thickness plus screed boards on top but worried about point loads from the toilet and shower, not to mention damp coming through

Does anybody have any alternative suggestions?

Thanks
Adrian

 

[endecotp]

Presumably you're considering extruded polystyrene because it is stronger than PIR. The alternative is to use better-insulating PIR (celotex, Kingspan) with wooden battens between the boards to give extra support. Or you could position them specifically to support the bath. See e.g. Pages 5 and 9 of http://www.kingspaninsulation.co.uk...22-97bb-5861799ab02a/Thermafloor-TF70-pdf.pdf

Actually you have a shower, not a bath; the load will be less. And I don't think a toilet is much more of a point load than a person standing.

Are you proposing screed board rather than plywood because it is more water-resistant? Really whatever you use you don't want any significant dampness getting below the final floor covering.

 

[adrian.groves]

Thanks endecotp.

Given that I only have 2 inches (insert your own joke) the better insulation and joists would be a better idea. Do I need to leave any air gap under the insulation to allow air to flow and install air bricks?

 

[adrian.groves]

Sorry, Ignore my last question, I have now read pages 5 and 9 as you suggested. Thanks I will use that system with 50mm timbers and the Kingspan